A poll of more than 1,000 likely voters in the United States released this week showed that in the last two years Americans have become more convinced that global warming is happening. An increasing number also believe there is a link between the increase in temperature and severity of weather events, such as hurricane Katrina, which has affected many and etched unpleasant memories in people’s minds. The poll was conducted by Zogby International for the National Wildlife Federation. The results: * 74 percent are more convinced that global is happening than they were two years ago, while only one in five are now less convinced. * 70 percent of respondents also linked severe weather to global warming. * 68 percent thought that hurricanes such as Katrina were influenced by the increase in global temperatures. (Scientists say no single hurricane can be taken as evidence of global warming, and while the topic is very controversial among experts, some scientists argue that global warming has contributed to the intensity of hurricanes in recent decades. Hurricanes are not the only potential indicators of global warming. […]